Today's planar digital image sensors simply inherit their form factor from the substrates and semiconductor processes used in their volume manufacture. But more and more research groups are pursuing the benefits of curved hemispherical sensors, mimicking the optimized optics of biological eye systems.

A concave version of the digital image sensor (left)
bends inward for creating a hemispherical focal plane
array while the convex version (right) mimics an insect’s
compound eye. Yei Hwan Jung and Kan Zhang.

Interestingly, because the active layer are so thin, the same folding mechanism can be implemented for both concave and convex photodetector arrays. The paper also highlights that the origami-based fabrication eliminates the use of metal wires in-between pixels, for the connection of sparsely arrayed devices, instead the jointing folds allow for densely packed pixel arrays. For a better fit, as design resolution increases, the edges of the hemisphere-like structure can be further smoothed out by dividing large pentagonal and hexagonal faces into smaller polygon faces.